Packaging containers

ABSTRACT

A packaging container and method of making same in which the finished container has a sealing fin extending upwardly from the top of the container and transversely of the container, said fin comprising two sections of the container blank which are heat sealed together by the use of a layer of thermoplastic material on the sections said layer being molecularly oriented in the longitudinal direction of the fin so that opening of the package may be facilitated.

United States Patent 1 1 3,9 4, 96

Rausing et a]. Dec. 9, 1975 PACKAGING CONTAINERS 3,175,250 3/1965 Bump229/17 G [751 Gad Anders Ram-M99881- 3533 35 351323 k223i? 15 5/18;Stark, Rydsgard; Sven 3,386,876 6/1968 Wyckoff 161/109 Costa U110Sevrell, Lund, all f 3,649,437 3/1972 Wolinski et al. 161/402 Sweden3,682,730. 8/1972 Haase 161/160 3,688,934 9/1972 Linder 215/32 [73]Assignee: Tetra Pak Developpement SA,

Lausanne, Switzerland Primary ExaminerGeorge E. Lowrance [22] Flled'June 1972 Attorney, Agent, or Firm-Pierce, Scheffler & Parker [21] Appl.No.: 266,721

30 Foreign Application Priority Data [57] ABSTRACT July 8, 1971 Sweden8821/71 A packaging container and method of making same in which thefinished container has a sealing fin extend- [52] US. Cl 229/17 G;161/402; 229/3.5 R; ing upwardly from the top of the container andtrans- 229/37; 229/51 TS versely of the container, said fin comprisingtwo sec- [51] Int. Cl. B65D 5/74 tions of the container blank which areheat sealed to- [58] Field of Search 229/37, 17 G, 3.5 R; gether by theuse of a layer of thermoplastic material 161/402, 160, 232, 250, 270,402; 220/27 0n the sections said layer being molecularly oriented in thelongitudinal direction of the fin so that opening [56] References Citedof the package may be facilitated.

UNITED STATES PATENTS 1,157,462 10/1915 Van Wormer 229/17 G 3 Claims 6Drawmg F'gures US. Patent Dec. 9, 1975 Sheet 1 of2 3,924,796

U.S. Patsnt Dec. 9, 1975 Sheet 2 of2 3,924,796

PACKAGING CONTAINERS The present invention relates to a packingcontainer of the type that is manufactured from a web or a flat blank ofa thermoplastic-coated carrier material by folding and hot-sealing ofthe packing material, the intention being to close the packing containerformed after filling by means of sealing along a sealing fin whichextends transversely across the packing containers.

In the manufacture of disposable packages, especially for liquids, apacking material is often used which consists of a carrier layer whichis coated, at least on the side which is intended to form the inside ofthe packing containers, with a homogeneous, heat-sealable plasticmaterial. The carrier material used most commonly is paper or cardboardand the coating material occurring most commonly is probablypolyethylene, and the packing material is manufactured most fre quentlyin the form of a web, from which either package blanks are punched out,or from which the packing containers are made by folding the web into atube which is then sealed along its longitudinal edges, whereupon thetube can be filled with the filling goods and be sealed up to individualpackages by means of successive transverse sealings at a distance fromone another.

If the packing containers are intended to be manufactured from blanks,these are punched out first, as mentioned above, from the packingmaterial web, whereupon the said blanks are formed to packing containersby folding them along folding lines, preferably provided in advance,which facilitate the folding, and these packing containers are thenclosed by heat-sealing, which is made possible by virtue of the saidthermoplastic coatmgs.

The packages of the abovementioned type, which are manufactured of paperor cardboard with a thermoplastic layer of e.g. polyethylene, arerelatively hard to open, however, since the carrier material layer isdifficult to tear and the thermoplastic layer supplies a tough innermembrane which renders more difficult the ripping open of the packages.To facilitate the opening of these known packages it is customary toarrange tearing indications in the package walls in the form ofperforations partly breaking through the package walls. It has becomeapparent, however, that these tearing indications are not as effectiveas would be desired, and that it is difficult besides to arrange thesetearing indications in the packing material in such a manner that anabsolute guarantee exists that the packaging material will not becompletely punched through.

To overcome the disadvantages mentioned above it is suggested inaccordancewith the present invention to provide a packing containerwhich is characterized in that the carrier material is made ofpolystyrene foam which is coated with one or more plastic layers of oneor more thermoplastic materials which plastic layer or layers is or aregiven molecular orientation in a direction which coincides with thelongitudinal direction of the said sealing fins.

The invention concerns the manner of manufacture of a packing containerin accordance with the invention, which manner is characterized in thata web of polystyrene foam is coated by extrusion with one or morehomogenuous layers of thermoplastic material, the coating being carriedout so that the speed of the 2 web is kept higher than the speed atwhich the thermoplastic material issues from the extruder, which has theresult that the thermoplastic layer or layers is or are subjected to amolecule-orientating stretching in connection with the coating, that thepacking blanks are punched from the web, the said blanks at the punchingbeing orientated in such a manner in relation to the web, that the partswhich are intended to form the sealing fins of the packing containersare orientated in the longitudinal direction of the web.

The invention will be described in the following with reference to theenclosed diagrammatic drawing, in which;

FIG. 1 shows a packing material web indicating a row of packing blanksarranged one after the other,

FIG. 2 shows a finished package and how the same is opened,

FIG. 3 shows a method for the manufacture of'packing material forpackages in accordance with the inven tion, and

FIG. 4 shows an enlarged cross-section through a packaging material web.

FIG. 1 shows a packing material web' 1, on which packing blanks 2 arearranged one after the other. In the figure are shown the packing blanks2 before they are separated from the web but after the folding linesfacilitating the folding have been put on the web 1. As is apparent fromFIG. 1, the packing blanks 2 are oriented across the packing materialweb 1, and each packing blank 2 has four side walls 4 and a longitudinaljoint section 13, which is intended to be used as a connecting sectionwhen the packing blank 2 through folding has acquired tubular shape withsquare or rectangular cross-section. Each one of the packing blanks 2 isprovided moreover with top closure sections 5,9,10, and bottom closureflaps 7,8,11. The hatched areas 6 are meant to be punched away from theweb and the punched away material has to be removed as unavoidablewaste.

The top closure sections of the packing blank 2 comprise two rectangularsections 5 and two triangular sections 9, the sections 5 and 9 beingjoined to one another by means of triangular backfolding sections 10.The rectangular sections 5 as well as the backfolding sections 10 arejoined moreover to the sealing section 3.

At the formation of the top of the packages the triangular sections 9are folded in towards one another over the opening of the packingcontainer, the backfolding sections 10 coming to be located between therectangular sections 5 and the triangular sections 9. The closuresections 3 will be placed together to form a flattened sealing fin 16.

The bottom of the package is formed in a similar manner as the top ofthe package, but with the difference that the bottom-forming flaps7,8,11,12 are not connected to any sealing section, but the sealing ofthe bottom is done in that the longer of the rectangular bottom sections8 with its outer part has to overlap the shorter rectangular flap 7 andthat all the bottom-forming sections are folded together in a flatbottom which is pressed together between heated surfaces so that thethermoplastic coatings are made to melt and retain the bottom-formingsections in the position where they are inserted in each other.

In FIG. 2a is shown a finished package in which the folded togetherclosure sections 3 form a sealing fin 16. The sealing sections 3 aresealed to each other along a sealing region 17, which in the case shownhere does not extend over the whole height of the sealing fin 16.

By arranging the top closure of the package in the above manner a tightand stable package is obtained. However, if the package is to bemanufactured e.g. of cardboard it will be very difficult to. open iteven if scissors or a knife are used, since it will be necessary to cutor clip through four layers of cardboard below the sealing area 17 ofthe sealing fin, that is to say in the area marked 18 in FIG. 23.

If the packing material instead of cardboard is made of foamed plastic,e.g. an extruded polystyrene foam which is coated with a layer ofhomogeneous plastic oriented in longitudinal direction of the web theopening work will become considerably easier, owing to the fact that anextruded film of polystyrene foam will be readily tearable without anyweakening being provided beforehand in the packing material. Thishomogeneous foamed plastic layer can in fact be readily torn inorientation direction, whilst it is very difficult to rip it in otherdirections. By using in this manner a polystyrene foam as a carrierpacking material and an oriented homogeneous plastic film, preferablypolystyrene film, as a coating material on the carrier layer, thepacking material can very easily be torn in the direction of orientationof the homogeneous plastic layer whilst it can be torn only withdifficulty in other directions. As it is desired in the present case toopen the package by ripping up the sealing fin 16 below the sealingregion 17, the packaging blanks are punched out of a web in the manneras shown in FIG. 1, where the carrier packing material layer consists ofextruded polystyrene foam and the homogeneous plastic layer consists ofpolystyrene film which is molecule-oriented in longitudinal direction ofthe web. Since the homogeneous plastic layer in the embodiment shownhere has its direction of orientation in the same direction as thelength of the sealing fin 16, it becomes simple to rip off the sealingfin 16 along the area 18 below the sealing region 17, but for furtherfacilitation of the tearing it is of course possible to provide a lightperforation or slotsalong the tearing area 18.

When the sealing fin 16 has been ripped up along the ripping area 18, asillustrated in FIG. 2b. the ripped-up parts of the fin 16 are folded outor torn off, whereupon the folded-in triangular flap 19 can be pulledout in the manner as shown in FIG. 20 to form a rhomboidal opening 20,through which the contents in the packages 14 become accessible.

The invention also relates to the manner of manufacture of a packingmaterial of the kind which is used in packages in accordance with theinvention, that is to say a packing material which consists of a web ofpolystyrene foam with a coat of homogeneous, moleculeoriented plasticmaterial, which is molecule-oriented in the direction of the web. Thehomogeneous plastic material may preferably consist of homogeneouspolystyrene film and the polystyrene foam web can likewise preferably beextruded. In Flg. 3 is shown how a previously manufactured, extrudedpolystyrene foam web 30 is rolled off a cylinder and is passed overguide rolls 26,27 and subsequently underneath an extruder 31. Throughthe extruder 31 is extruded a homogeneous polystyrene film 32 which isplaced on the polystyrene foam web 30, whereupon the coated web 30 isintroduced between cooled press rolls 28,29 for a lamination of thematerial.

By keeping the speed of the web 30 appreciably higher than the speed ofextrusion of the polystyrene material from the extruder 31, a stretchingof the extruded polystyrene film 32 takes place, which stretching may bebetween 5 and 20 times. By virtue of the stretching in conjunction withthe lamination a molecule orientation of the extruded polystyreneplastic is achieved which, as described earlier, has the result that thelayer of polystyrene plastic can readily be ripped open in the directionof orientation, whilst it can be torn only with difficulties in otherdirections.

Finally in FIG. 4 is shown an enlarged cross-section through amanufactured packing material web, the polystyrene foam layer beingmarked 30 and the extruded and oriented homogeneous polystyrene layermarked 32.

It was found that an excellent packing material for the abovementionedpurpose is obtained when a previously extruded polystyrene foam web of athickness between 0.25 and 1.5 mm is coated with a homogeneouspolystyrene film which in this orientated layer has a thickness between0.02 and 0.2 mm. It was found that plastic material other thanpolystyrene can also be used as a coating layer, and it was foundpossible for example to use polyethylene or polypropylene. The bestresults were achieved, however, with polystyrene as a coating material.

It is also possible of course to coat the outside of the polystyrenefoam with a plastic layer so as to enhance the appearance of thepackage. The polystyrene foam material is not moisture-absorbing in thesame manner as paper or cardboard however, and an outside coating ofplastic material is therefore not essential as a protection of thepackages against atmospheric moisture.

We claim:

1. In a packaging container formed from a flat blank of a polystyrenefoam packaging material having at least one layer of at least onehomogeneous thermoplastic material thereon, the container having, at thetop thereof, a sealing fin extending upwardly from the top of thepackage and transversely thereacross, said fin being formed by heatsealing together two sections of the blank, the improvement wherein theat least one layer of at least one homogeneous thermoplastic material onthe sections forming the fin are molecularly oriented only in thelongitudinal direction of the sealing fin across the top of thecontainer, to facilitate tearing said fin to open the container.

2. A packaging container as claimed in claim 1 wherein the at least onehomogeneous thermoplastic material is selected from the group consistingof polystyrene, polyethylene and polypropylene.

3. A packaging container as claimed in claim 1 wherein the at least onehomogeneous thermoplastic material is polystyrene.

1. IN A PACKAGING CONTAINER FORMED FROM A FLAT BLANK OF A POLYSTYRENEFOAM PACKAGING MATERIAL HAVING AT LAST ONE LAYER OF AT LEAST ONEHOMOGENEOUS THEREMOPLASTIC MATERIAL THEREON, THE CONTAINER HAVING, ATTHE TOP THEREOF, A SEALING FIN EXTENDING UPWARDLY FROM THE TOP OF THEPACKAGE AND TRANSVERSELY THEREACROSS, SAID FIN BEING FORMED BY HEATSEALING TOGETHER TWO SECTIONS OF THE BLACK, THE IMPROVEMENT WHEREIN THEAT LEAST ONE LAYER OF AT LEAST ONE HOMOGENEOUS THERMOPLASTIC MATERIAL INTHE LONGITUDINAL DIRECTION OF THE SEALING FIN ACROSS THE TOP OF THECONTAINER, TO FACILITATE TEARING SAID FIN TO OPEN THE OF THE CONTAINER,TO FACILITATE TEARING SAID FIN TO OPEN THE CONTAINER.
 2. A packagingcontainer as claimed in claim 1 wherein the at least one homogeneousthermoplastic material is selected from the group consisting ofpolystyrene, polyethylene and polypropylene.
 3. A packaging container asclaimed in claim 1 wherein the at least one homogeneous thermoplasticmaterial is polystyrene.